Stabilizing thiirane compounds

ABSTRACT

WHERE R4 AND R5 CAN EACH BE H, AND ALKYL GROUP OF 1-8 C ATOMS PHENYL OR HALOPHENYL GROUPS AND R6 IS AN ALKYLENE GROUPS OF 1-8 C ATOMS.   A-C(=S)-NH-R   WHERE R IS H, AN ALKYL GROUP OF 1-8 C ATOMS OR AN ALKENYL GROUP OF 3-8 C ATOMS, AND A IS AN ALKYL GROUP OF 1-8 C ATOMS, AN ALKOXY GROUP OF 1-8 C ATOMS,   R2-N(-R3)-   WHERE ONE OF R2, R3 CAN BE H AND ONE OR BOTH CAN BE ALKYL OF 1-8 C ATOMS, PHENYL OR HALOPHENYL GROUPS, OR   THIIRANES ARE STABILIZED AGAINST POLYMERIZATION BY BLENDING WITH FROM .01 TO ABOUT 5 PERCENT BY WEIGHT OF COMPOUNDS HAVING THE STRUCTURE R4-N(-R5)-C(=S)-R6-

United States Patent i 3,557,145 STABILIZING THIIRANE COMPOUNDS Russell T. McFadden, Jones Creek, Tex., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware No Drawing. Filed May 13, 1968, Ser. No. 728,748 Int. Cl. C07d 59/00 U.S. Cl. 260327 21 Claims ABSTRACT OF THE DISCLOSURE Thiiranes are stabilized against polymerization by blending with from .01 to about percent by weight of compounds having the structure where one of R R can be H and one or both can be alkyl of 1-8 C atoms, phenyl or halophenyl groups, or

where R, and R can each be H, an alkyl group of 1-8 C atoms phenyl or halophenyl groups and R is an alkylene group of 1-8 C atoms.

This invention relates to a mixture of a thiirane and a stabilizing agent to reduce the degree of or prevent polymerization of the thiirane and to a method of stabilizing the thiirane by blending with certain thioamides and more particularly pertains to mixtures of (1) at least one vicinal thiirane and (2) at least one compound of the structure s H II A- N Where R represents H, an alkyl group of l to 8C atoms, or an alkenyl group of 3 to 8 C atoms, and A represents (1) an alkyl group of 1-8 C atoms, an

alkoxy group of 1-8 C atoms, a phenyl group or a halophenyl group, (2)

where not more than one of R or R, can be H and 3,557,145 Patented Jan. 19, 1971 ice the other or both can be an alkyl group of 1-8 C atoms, a phenyl or a halophenyl group, or (3) where R, and R can each be H, alkyl of 1-8 C atoms, phenyl or halophenyl groups and R is an alkylene group of from 2 to 8 C atoms, and to a method of stabilizing the thiiranes by dissolving therein a small but effective amount of at least one compound of the structure defined above.

Thiiranes, or alkylene sulfides or episulfides of the structure wherein Y and Y can each represent H, an aliphatic hydrocarbon group, an aromatic hydrocarbon group or a cycloaliphatic group and halogen, SH, OH, ester, CN, polyoxyalkylene and polythioalkylene groups and substituted derivatives thereof, have a great propensity toward spontaneous polymerization when stored, either as individual components or as mixtures, even when the thiiranes are highly purified and are substantially free of water.

Previous means for stabilizing thiiranes are based on the addition of H 8, alkyl or aryl mercaptans or a mixture of one of these SH containing compounds with a linear thioether. The stabilizers of the prior art are satisfactory for prevening polymerization of the thiiranes at low temperatures to a storage period of about a week or for short periods of storage at vacuum distillation temperature. However, they are difficult to separate from the thiirane because of their volatiliy. The H 8 or mercaptans can be removed by chemical means, but great care must be exercised to avoid polymerization of the thiirane. In addition, H 5 and mercaptans will react slowly with the thiiranes so that on prolonged storage the stabilizing compounds are converted to derivatives which either no longer have polymerization inhibiting activity or have this activity in a very greatly reduced degree.

One of the advantages of this invention is that the compounds of the structure H A- NR where A and R have the designation given above, will stabilize thiiranes against polymerization during extended periods of storage. Another advantage is that the storage temperature can be as high as about 60 C. A further advantage is that the stabilizers are effective even in bright daylight in glass containers. A still further advantage is that the thiirane can be separated from the stabilizer by simple distillation 'because of their relatively high boiling points as compared with the boiling points of the thiiranes. Yet another advantage is that the stabilizers are effective at relatively low concentrations.

The above advantages are obtained from a mixture comprising .01 percent to about 5 percent by weight, preferably from about 0.1 to about .5 percent based on the thiirane of at least one compound having the structure where A and R have the defined designation. The thiirane can be any one or a mixture of compounds of the structure as defined. The mixture can contain one or more inert diluents, which include but are not limited to liquid alkanes, aromatic hydrocarbons, liquid monoand polyhydric alkanols, liquid alkyl and aromatic ethers, esters, alkyl sulfides, alkyl disulfides, ketones and halogenated derivatives of the above diluents and alkyl substituted aromatic hydrocarbons. Representative diluents are hexane, saturated liquid petroleum distillates, benzene, toluene, xylene, methanol, propanols, butanols, pentanols, hexanols, heptanols, octanols, diethyl ether, dipropyl ethers, dibutyl ethers, methyl butyl ether, methylene chloride or bromide, dichloro or dibromo ethane, chloro and bromobutanes, perchloroethane, chlorobenzene, chlorotoluene, chloroxylene, propyl sulfide, ethyl acetate, and acetone. The method of obtaining the advantages of this invention comprises commingling or blending of the defined essential ingredients. Any blending order can be used. Either the thiirane, stabilizer or both or mixtures of thiiranes with mixtures of stabilizers can be commingled with or without inert diluents, which if used, can be added before, during or after blending The specific thiiranes that can be protected against polymerization by commingling with the stabilizers of this invention include thiirane (ethylene sulfide), 1,2- propylene sulfide, 1,2-butylene sulfide, 2,3-butylene sulfide, 1,2-pentylene sulfide, 2,3-pentylene sulfide, 1,2- 2,3- and 3,4-hexylene sulfide, 1,2-octylene sulfide cyclohexene sulfide, l-phenyl ethylene sulfide, 1-phenyl-2,3-propylene sulfide, 2-phenyl-1,2-propylene sulfide, 1-(2-methoxyphenyl)-2-3 propylene sulfide, 1-(2-methylphenyl)-l,2- ethylene sulfide, 1-(2-methylphenyl)-2,3-propylene sulfide, l-(2,3-dimethylphenyl)2,3-propylene sulfide, 1-(2,4- dimethylphenyl)-2,3-propylene sulfide, 1-chloro-2,3-propylene sulfide, l-bromo-2,3-propylene sulfide, l-hydroxy- 2,3 propylene sulfide, 1 methoxyl-2,3-propylene sulfide, 1-mercapto-2,3-propylene sulfide, allyl thioglycidyl ether and mixtures of any of these alkylene sulfides.

The thiiranes vary considerably in their inherent reactivity. The most diflicult to maintain in the monomeric state is thiirane The next higher homologue, 1,2-propylene sulfide H20H0H3 can, if sufiiciently purified, be kept in the monomeric state at temperatures close to 0 C. for an extended period of time. Cyclohexene sulfide can be stored at room temperature for about a week, but it will form a polymer slowly on standing and at elevated temperature it will polymerize fairly rapidly. In mixtures, the most reactive thiirane appears to be no more stable than it is alone, so that when it starts polymerizing it will tend to accelerate the homo or copolymerization of the more inherently stable thiirane with which it is commingled or blended.

The compounds which act as polymerization inhibitors or stabilizers for monomeric thiiranes all have a thioamide or substituted thioamide group. Included among these compounds are thioacetamide, thiopropionamide, thiobutyramide, thiocapramide, dithiooxamide, dithio- 4 succinamide, dithioadipamide, N-phenyl thiourea, N-allyl- N,N'-disopropyl thiourea, thiobenzamide, thiophenylacet amide, methyl thiourethane, (N-allyl)butyl thiourethane, (N-allyl)ethyl thiourethane and actylthiourethane, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl thioncarbamates.

If the stabilizers are added as solutions in an inert solvent, it is preferred, but not necessary, that the solvent employed is also a solvent for the thiirane. In any event, the stabilizer must be soluble in the thiirane compound.

The examples which follow are intended to illustrate but not to limit the invention. In all instances parts are given by weight unless otherwise specifically indicated.

EXAMPLE 1 A mixture of 5 weight parts of thiirane CHgCHz and .05 weight parts of thioacetamide was stored in glass containers outdoors, exposed to summer weather in Texas at daytime temperatures of about 100' F. The sample was checked periodically for signs of polymer formation. After one week there appeared to be only an extremely slight amount of polymer formation at the liquidglass interface. The remainder of the thiirane was liquid and completely clear. The thiirane is easily separated from the thioacetamide by distillation.

For comparative purposes a sample of the thiirane containing no inhibitor and samples each containing 1 percent by weight, based on the thiirane, of mercaptoethanol, allyl mercaptan, thioglycolic acid and t-octylmercaptan were subjected to the same storage conditions as described above. Within 48 hours all these comparative mixtures were turbid and after one week all the comparative samples developed copious amounts of precipitate.

EXAMPLE 2 A series of samples using various stabilizers or polymerization inhibitors was prepared by dissolving the stabilizer in thiirane. The mixtures were stored in glass containers under substantially identical outdoor summer conditions in Texas. A control sample having no stabilizer was included in the series. In the table below are listed the stabilizers and concentrations used in the tests.

Concentration Stabilizer weight percent N-phenyl thiourea 0. 5

Thioacctamidc 0. 1

. II II Dithioadipannde (HzN -C CH2)4C-NH2) 0. 5

N-allyl-N,N-diisopropylthi0urea 0. 5

After 21 days all the samples containing the stabilizers listed in the table were liquid and clear. The control containing no stabilizer was polymerized.

EXAMPLE 4 A series of difierent thiirane compounds was prepared containing various amounts of thioacetamide as polymerization inhibitor. These samples were stored in an oven at F., and the viscosities were measured after four weeks. The sample compositions and viscosities are shown in the following table.

, Viscosity after storage at Weight of 130 F. forthioaeetamide, W Weight of thiirane, gm; gm. days 28 days Sam le Number:

1. A Thioeplehlorohydrln, 50... 1.0 t). 7 0.8 0.5 0.7 1.0 C Thloepichlorohydrin, 0. 0 0. 6 1. 3

2. A 1,2-propylene sulfide, 50 1.0 0. 5 0. 5 B d 0. 5 0. 4 0. 6 0. 0 0. 4 1. 1

3. 1. 0 0. 5 0. 5 o---. 0.5 0.4 0.6 1,2-butylene sulfide, 10.0 0. 0 0. 4 0.9

4. A Allyl thioglycldyl ether, 50 1. 0 0. 6 0. 6 B d 0. 5 0. 6 0. 6 C Allyl thioglycidyl ether 10.0 0.0 0.5 0. 9

1 Viscosity was measured by the time in seconds required for a bubble to traverse the specified distance in an inverted Gardner-Holdt viscosity tube, at 25 0.

-CH SCH CH=CH In this example ethylthioncarbamate (C H O or 2 CSNH was employed as a stablizer for ethylene sul- 5 K gi ig i gg gggf kig i g g g gi fide and propylene sulfide. The ethylthioncarbamate was g P y g added to the 50 g. of the thiirane in glass bottles to Pro- Eifg on sald thmane a compound havmg the Struc vide deiferent levels of stabilizer concentrations and then subjected to 55 C. storage for accelerated testing. The i f data obtained are tabulated in the following table.

Observations Grams of Thilrane C H 0CSNH 1 week 2 weeks 3 weeks Ethylene sulfide 01. 0 No precipitation No precipitation Very light precipitation.

o o 0. None Light preeipltatiom.-. Medium precipitation- Heavy precipitation.

Propylene sulfide 0.5 No thickening.. N0 thickening No thickening.

0.1 do .do Slight thickening. None .do ..do Definite thickening.

It is apparent that the thioncarbamate protects the wherein R is (a) H, an alkyl group of from 1 to 8 carmore stable thiirane from polymerizing at relatively high bon atoms or an alkenyl group of 3-8 C atoms and A temperatures and is capable of preventing the most acis an alkyl group of 1-8 C atoms, an alkoxy group of 1-8 tive thiirane from polymerizing for more than two weeks C atoms, a phenyl or a halophenyl group, (b) at high storage temperature.

The unusual ability of the compounds having the struc- R2 ture N II H a A-C-N-R as ddefined, for stabilizing thiiranes has been exemplified Where One Of 2, 3 can be H and one Or both Can b by showing their superior effectiveness in inhibiting the an alkyl group of 1-8 atoms, a phenyl or halophenyl polymerization of ethylene sulfides, the most reactive of group of the thiirane series as well as other thiiranes having up to 6 C atoms, including a halogen substituted and an ff alkoxy substituted thiirane. It is to be understood that all the remaining thiiranes defined by the generic formula R Y-CHCHY where R; and R can each be H, an alkyl group of 18 C atoms, a phenyl or a halophenyl group and R is an are also stabilized by the compounds of the formula alkylene group of 2-8 C atoms.

i H 2. The composition of claim 1 in which the thiirane is I claim: A CN R H 1. A composition consisting essentially of (1) a this irane of the formula E 3. The composition of claim 1 in which the thiirane is CH3CH-CH2 wherein Y is H or an alkyl group of 1 to 2 C atoms, s and Y is H, an alkyl radical having 16 C atoms, inelusive, 4. The composition of claim 1 in which the thiirane is CICH2CHOH2 -0H2 -CH;, CHz I CH3, OCHa,

5. The composition of claim 1 in which the compound -CHz S H CH3, (C1192 A lN is an amide of a thioacid having from 2 to 8 carbon atoms.

6. The composition of claim 1 in which the compound is a mono N-substituted thiourea in which the substituent is a hydrocarbon group of from 1 to about 6 carbon atoms.

7. The composition of claim 1 in which the compound i t A-CNR is a substituted thiourea in which each nitrogen is monosubstituted with an aliphatic hydrocarbon group of from 1 to 8 carbon atoms.

8. The composition of claim 1 in which the thiirane is and the stabilizer is thioacetamide.

9. The composition of claim 8 in which the stabilizer is N-phenyl thiourea.

10. The composition of claim 8 in which the stabilizer is N-allyl-N-N-diisopropyl thiourea.

11. The composition of claim 8 in which the stabilizer is dithioadipamide.

12. The composition of claim 8 in which the stabilizer is ethylthioncarbamate.

13. The composition of claim 1 in which the thiirane is allyl thioglycidyl ether.

14. The composition of claim 1 in which the thiirane and the stabilizer is thioacetamide.

15. The composition of claim 14 in which the stabilizer is N-phenyl thiourea.

16. The composition of claim 14 in which the stabilizer is N-allyl, N-N'-diisopropyl thiourea.

17. The composition of claim 14 in which the stabilizer is dithioadipamide.

18. A method of inhibiting the polymerization of thiiranes having the structure wherein Y is H or an alkyl group of 1 to 2 C atoms, and Y is H, an alkyl radical having 16 C atoms, inclusive,

-CH Cl, -CH Br, CH OH, CH OCH CH SH, or CH SCH CH=CH or Y and Y together form 15 (CH of a cyclohexyl group, comprising commingling said thiirane with from 0.01 to about 5 percent by Weight, based on said thiirane, of a soluble compound of the structure A-( iNR wherein R is (a) H, an alkyl group of l-8 C atoms, or an alkenyl group of 38 C atoms and A is an alkyl group of 1-8 C atoms, an alkoxy group of 1-8 C atoms,

a phenyl or a halophenyl group, (b)

where one of R and R can be H and one or both can be an alkyl group of 1-8 C atoms, a phenyl or a halophenyl group and R is an alkylene group of 2-8 C atoms.

19. The method of claim 18 in which the thiirane is and the stabilizer is thioacetamide.

20. The method of claim 18 in which the thiirane is and the stabilizer is thioacetamide.

21. The method of claim 18 in which the stabilizer is N-phenyl thiourea.

References Cited UNITED STATES PATENTS 3,317,919 5/1967 Sander 260-79 HENRY R. JILES, Primary Examiner C. M. SHURKO, Assistant Examiner 

